Water supply system

ABSTRACT

This invention relates to evaporative heat exchangers and in particular to improved apparatus for the distribution of water over a heat exchange surface.

[151 3,659,623 [451 May 2,1972

United States Patent Facius [56] References Cited UNITED STATES PATENTS [54] WATER SUPPLY SYSTEM [72] Inventor: Thomas F. Faclus, Baltimore, Md.

XX X 6722 71/1. BUM 75.... 36 "6 all "2 J 1 mm mm h mh mm m hmmm SkS ncn WEEE 6446 1666 9999 1111 H H l 11 awn 1 1 5680 0459 2 2 [I333 Remed s. Appnmflon m Primary Examiner-Henry T. Klinksiek Assistant Examiner-Robert J. Miller [63] Continuation of Ser. No. 425,783, Jan.

Attorney-Stevens, Davis, Miller & Mosher abandoned.

437/255, 137/262, 261/! 12 ABSTRACT ----.--Fl6k51/00 This invention relates to evaporative heat exchangers and in 137/255, 259, 262, 264, 265, particular to improved apparatus for the distribution of water 137/2 5 239/ 93; 261/ I I2, l 1 1 8 over a heat exchange surface.

[52] 0.8. [51] Int. [58] Field ofSearch..................

4 Claims, 4 Drawing Figures Patented May 2, 1972 3,659,623

2 Sheets-Sheet l REF. OUT

WATER SUPPLY SYSTEM This application is a continuation of application Ser. No. 425,783, filed Jan. 15, 1965 now abandoned.

In the art of evaporative heat exchangers, the usual practice is to spray water which flows by gravity in droplet or rain-like form countercurrent to air which flows upwardly through the heat exchange area. During this period of contact, some of the water evaporates and the heat of vaporization is extracted from whatever is to be cooled. Such systems are commonly used to cool fluids, to condense and cool refrigerants, to cool water, etc. In the cooling of water, some of the water is evaporated and the heat of vaporization is extracted from the remaining water which is thus cooled.

In a countercurrent system, it is necessary that the equipment which sprays water across the top of the heat exchanger be so constructed that air can pass through and around it. To this end, it has been common to make a grid of pipes above the heat exchanger and to provide these with nozzles from which the water is sprayed. While this arrangement works satisfactorily, it is expensive to construct and to maintain. Individual nozzles have to be used and the pipe has to be installed to reasonably high standards. A pump capable of developing enough head to deal with the resistance imposed by the nozzles is, of course, required.

A water distribution system involving troughs spaced apart so that air could flow between them is disclosed in US. Pat. No. 3,146,609. This invention involves an improvement over the disclosure of that patent.

To insure uniform flow from notched troughs in a countercurrent evaporative heat exchange system, the problem is one of maintaining a large volume of water in the troughs and supplying that volume in such manner that velocity efi'ects do not impair the evenness of the flow at different points along the length of the trough.

It is an object of this invention to provide a water system which will supply large volumes of water under conditions of very low turbulence so that flow from the troughs is uniform throughout the length.

Other objects and advantages of this invention will be apparent upon consideration of the following detailed description of several embodiments of heat exchange equipment incorporating this invention and disclosing as well the invention of the concurrently filed application of John Engalitchefi', Jr. in conjunction with the annexed drawings wherein:

FIG. 1 is a schematic view in vertical section of an evaporative condenser incorporating the water distribution system of the present invention; I

FIG. 2 is a schematic view in vertical section of an evaporative cooler also incorporating the water supply system of the present invention;

FIG. 3 is a view to an enlarged scale of a single trough and the water supply system for feeding the same; and

FIG. 4 is a view partly in section and partly in elevation taken along the line 4-4 of FIG. 3.

Referring now to the drawings in greater detail and in particular to the FIG. 1 thereof, it will be noted that chamber is provided at its upper end with a group of troughs 11 and at its lower end with a sump 12. Each trough has V notches 13 in its side walls (see FIG. 3), those in one side wall being staggered in relation to those in the other side wall. Water spilling from the notches 13 of the troughs 11 passes through heat exchanger tubes 14 in the form of rain or droplets and is collected in the sump 12 from which it is recirculated by a pump 15 through a conduit 16 to the troughs 11. Make-up water enters through a conduit 17 under the control of a float valve 18 operated by a float 19 disposed in the sump 12.

A centrifugal fan 20 pumps air through ducting 21 and this air flows upwardly through the chamber 10 countercurrently to the water issuing from the troughs 1 1. The air, after passage through the heat exchanger 14, passes between the troughs 1 1 and through mist eliminators 22 to atmosphere. As a fluid to have heat extracted from it is circulated through the heat exchanger tubes 14, heat is extracted by vaporization of the water wetting the exterior of the tubes 14, this water having spilled from the notches 13 of the troughs 11.

The foregoing is a brief description of an evaporative heat exchanger which is conventional in structure and operation except for the water distribution system of the present invention and the trough system of the concurrently filed application of John Engalitchefi, Jr.

It will be appreciated that if the heat exchanger 14 is used for a purpose such as condensing a refrigerant, the amount of water necessary to be supplied is only that amount required to keep the exterior of the tubes wet at all times. By the use of rounded bottom troughs the curvature of which is clearly apparent from FIG. 4, it is possible so to distribute the water issuing from these troughs that they may be spaced wide apart and indeed occupy only about 20 percent of the cross section of the chamber 10 at the plane A-A and, yet, insure that the tubes 14 are maintained wet at all times. The structure by which this is accomplished is best understood by reference to FIGS. 3 and 4.

A chamber 23 is located near the top of chamber 10 and is fed centrally from conduit 16. This chamber 23 is partially defined by a wall 24 which separates it from and is common to a reservoir 25. Reservoir 25 is defined by the partition 24, a common bottom wall 26 and a wall 27, which is the wall which one sees in FIG. 1. The wall 24 defines a series of spaced round holes 28 which provide a path of liquid communication between chamber 23 and reservoir 25. The wall 27 defines a group of discharge apertures, one for each trough 11, and these discharge apertures bear reference numeral 29. Four of them can be seen in FIG. 4. The apertures 29 generally conform to the cross section of the trough but they terminate below the steady water level in the troughs 11. The water issuing from the conduit 16 enters the chamber 23 near the center thereof, flows through holes 28 in partition 24 and establishesa stable liquid level in reservoir 25. Note that there is a hole at 28 for each three troughs. Chamber 23 is actually of about the same height as the diameter of pipe 16 so that the flow from the pipe to the chamber is about the same as the flow from the stem into a T joint. Reservoir 25 drains through apertures 29 into the respective troughs and from the V notches in the troughs the water spills into the heat exchange region. In so spilling, the streams have a tendency to adhere to the side wall of their originating notch and to leave the trough well'beyond the vertical center line on the side of the trough opposite to the notch of origination. These streams can be clearly seen by the broken line drawing in FIG. 4. The stream 30 issues from a notch in the right-hand side of the trough 11 as it is viewed in FIG. 4 and the stream 31 issues from a notch in the left-hand side of the trough 11 as it is viewed in FIG. 4. The notches 13 of the troughs 11 are staggered, asis quite apparent from FIG. 3, so that notches on opposite sides of the trough are mutually axially oflset with a result that streams, such as 30 and 31, are axially offset and do not interfere with each other.

Between the streams 30 and 31 and the vertical center line of the trough, there is defined an angle alpha and it has been discovered that this angle alpha is related to the curvature at the base of each trough. As can be seen in FIG. 4, the troughs illustrated in this application have nearly parallel sides connected by an arc of uniform radius. Whether such an arc is used as the radius of curvature of the bottom of the troughs is a matter of what is sought to be accomplished. If the troughs are in the form of a sharp V at the bottom, then the respective angle alpha will be quite small and the spacing between the troughs will have to be small in order to get good water coverage. Where good water coverage is sought with minimum obstruction of the air flow space, it has been found that the troughs, as illustrated in FIG. 4, are effective. The troughs of FIG. 4 are shown as rather widely spaced in FIG. 1 and occupy only about 20 percent of the cross sectional area of the chamber 10 at the plane A-A. This arrangement has been found to offer good wetting characteristics for evaporative condenser tubes and minimum resistance to air flow through the plane A-A. Clearly, the lack of resistance to air flow is an economical advantage as far as the power requirements of the air fan 20 are concerned.

The troughs 11 are supported in brackets 32 and 33. Each bracket 32 is provided with integral flanges at 34 and 35 which are bolted or fastened by self-tapping screws to the partition 27 with the trough in registry with the respective aperture 29 (see FlG. 4). Bracket 33 is similarly held by flanges 37, only one of which shows in the drawings. A matrix of sealing material indicated at 39 seals each end of each trough into the respective hanger bracket.

in FIG. 2, there is shown a system in most respects similar to that shown in FIG. 1. Coresponding portions have been correspondingly numbered. The water distribution is the same but the troughs 11 are spaced so close together that they occupy 45 percent of the cross section of the chamber at the plane A-A. The reason for this is that in FIG. 2, there is disclosed a cooling tower with undulatory plates 39 disposed in the heat exchange region. These plates 39 are provided to afford a large air-water interface so that large volumes of water may be cooled.

in the arrangement of FIG. 2, water, to have heat extracted from it, is delivered by pipe 40 and is discharged from the troughs 11 as described in conjunction with FIG. 1. Some of this water evaporates and this has the effect of cooling the rest of the water so that the hot water supplied through conduit 40 is cooled by the time it reaches the sump 12. The cool water is withdrawn from the sump 12 through a conduit 41.

It has been discovered, as a part of this invention, that by feeding water centrally to a chamber such as 23 which communicates with reservoir 25 through a number of spaced apart holes, there is possible to maintain a head of water in reservoir 25 which is relatively free of turbulence. Because the holes 29 are of the same general cross sectional shape and area as the troughs which they feed, there is very little velocity effect in the passage of the water through the ports 29 in the partition 27. The upper edge of each port 29 is below the spill level or level of the head of water in troughs 11. This is done deliberately to impart enough resistance to the water flowing into the trough so that the notches near the port 29 will spill a stable pattern and not be affected deteriously by a high velocity condition in the adjacent region of the trough.

What is claimed is:

l. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, an elongated reservoir, a common wall between said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports generally conforming to the interior cross sectional shape of the trough served,

2. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, an elongated reservoir, a common wall dividing said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports each conforming to the interior cross sectional shape of the trough served but with its upper defining edge in a plane slightly below the bottom of the trough notches.

3. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, means to feed water to said chamber centrally thereof, an elongated reservoir, a common wall dividing said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports confonning to the interior cross sectional shape of the trough served but with its u per defining edge in a plane slightly below the bottom oi the trough notches.

4. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, an elongated reservoir, a common wall dividing said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports having a cross sectional area slightly less than the cross section of that portion of the trough served lying below the bottom of the trough notches.

l il t l I 

1. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that cOmprises an elongated chamber, an elongated reservoir, a common wall between said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports generally conforming to the interior cross sectional shape of the trough served.
 2. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, an elongated reservoir, a common wall dividing said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports each conforming to the interior cross sectional shape of the trough served but with its upper defining edge in a plane slightly below the bottom of the trough notches.
 3. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, means to feed water to said chamber centrally thereof, an elongated reservoir, a common wall dividing said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports conforming to the interior cross sectional shape of the trough served but with its upper defining edge in a plane slightly below the bottom of the trough notches.
 4. A system for maintaining an even level of water in a series of troughs each having notched side walls and being spaced apart in the same plane that comprises an elongated chamber, an elongated reservoir, a common wall dividing said chamber and reservoir and defining holes at spaced intervals therealong, the wall of said reservoir opposite said common wall defining a plurality of outlet ports each communicating directly with an end of one of said troughs, said ports having a cross sectional area slightly less than the cross section of that portion of the trough served lying below the bottom of the trough notches. 